Switching Scenes causes EXC_BAD_ACCESS on touch events

cocos2d-x C++
#1

So i have a main menu scene that has a menu item that launches an in game scene:

auto scene = MeadowScene::createScene();
Director::getInstance()->replaceScene(TransitionFade::create(1, scene));

the MainScene is started in AppDelegate.cpp like this:

auto scene = MainScene::createScene();
Director::getInstance()->runWithScene(scene);

I have several event listeners for many interactive sprites on the MeadowScene. The Event listener looks something like this:

bool Snail::addTouchEvent() {
    auto listener = EventListenerTouchOneByOne::create();
    listener->setSwallowTouches(false);
    
    listener->onTouchBegan = [&] (Touch* touch, Event* event){
        listener->setSwallowTouches(true);
        // get the sprite from the event object
        auto sprite = event->getCurrentTarget();
        
        Vec2 pt = touch->getLocation();
        auto recTemp = sprite->getBoundingBox();
        
        if (recTemp.containsPoint(sprite->getParent()->convertToNodeSpace(pt) )) {
            Director::getInstance()->getEventDispatcher()->pauseEventListenersForTarget(sprite);
            this->animate(sprite);
            
        }
        return true;
    };
    Director::getInstance()->getEventDispatcher()->addEventListenerWithSceneGraphPriority(listener, this->sprite);
    return true;
    
}

When the MeadowScene is the first scene to load then everything works fine however when the MainScene replaces itself with MeadowScene then I start having issues. When the different interactive elements get touched I get this error:

Thread 1: EXC_BAD_ACCESS (code=1, address=0x178)

That happens in this function:

void EventListenerTouchOneByOne::setSwallowTouches(bool needSwallow)
{
    _needSwallow = needSwallow; // Thread 1: EXC_BAD_ACCESS (code=1, address=0x178)
}

Any idea why this might be happening? is there a step that I am missing in switching scenes?

#2

You are always returning true?

I’d return true in the if block and return false otherwise.

#3

I gave that a shot and that’s probably how I should do it but it was still giving me an error. I found the issue though:

listener->setSwallowTouches(false);

listener->onTouchBegan = [&] (Touch* touch, Event* event){
    listener->setSwallowTouches(true);

Removing the second call the setSwallowTouches worked.

#4

Yup, do you know why?

1 Like
#5

Is there a way to swallow the touch and prevent other event listeners from getting the event only if the element the event listener is for has been touched? i have an event listener per element. Or is the only way to do that to have a single global listener that handles it all for everything?

#6

Per element works just fine.

#7

No sir, I do not.

#8

First, this should be true.

Second you were experiencing a scope issue. You were calling listener inside a lambda of the same listener.

#9

That makes sense. Thank you for your help and very quick responses. What an awesome community

#10

Ask anything you need to. This is how we all grow as developers.

1 Like